The diagnostics and monitoring of structures, such as that carried out in the structural health monitoring field, are often accomplished by employing arrays of sensing elements coupled to a structure. These sensing elements then either passively monitor the structure for the presence of stress waves propagating therein, or actively interrogate the structure by generating such stress waves, where the stress waves have predetermined waveforms and amplitudes.
For many structures, it is desirable to employ a large number of sensors. Examples include large structures, and structures with many areas of high stress. Each sensor typically requires multiple wires or leads, so that simply dealing with the accurate placement of sensors, and placing their wires, becomes time consuming and cumbersome. Accordingly, some applications employ a flexible layer upon which both sensors and their wires are mounted. In this manner, only a single layer need be applied to the structure, rather than multiple individual sensing elements and their wires.
Such layers have their drawbacks, however. For instance, even though they may be flexible, it is sometimes difficult to conform such layers to highly curved or irregular structures without excessively folding or tearing them, as folds and tears risk damage to the sensing elements and their wires. Accordingly, efforts have been made to improve the conformability of such layers.